$\lim _{x \rightarrow 0}\left[\frac{\log (1+9 x)}{x}\right]$
\begin{aligned}
& \lim _{x \rightarrow 0} \frac{\log (1+9 x)}{x} \\
& =\lim _{x \rightarrow 0}\left[\frac{\log (1+9 x)}{9 x}\right] \times 9 \\
& =1 \times 9 \quad \ldots\left[\lim _{x \rightarrow 0} \frac{\log (1+x)}{x}=1\right] \\
& =9 \quad \text { }
\end{aligned}
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